In the begining of "Birthright. Part I" episode (Star Trek Next Generation 6x16) an Yridian tells Worf about a prison camp on Carraya IV
were Worf's father is kept alive (apparently not killed in Khitomer Massacre) as hostage.
But later, in the end of this episode and in the begining of "Birthright. Part II" we learn, that
there is absolutely no chance for anyone to leave the camp. Camp itself is placed on a remote plantet, forgotten by "entire universe" and no information ever leaves its borders. Anyone, who enters borders of the camp can either stay there for the rest of his/her life or be executed.
If that's so, then how could Yridian learn about this prison camp? I'm looking only for a canonical or at least logical explanation (if any of such exists), not about speculations.